Dataset Information

Culture types and period impact gametophyte morphogenesis and sporophyte formation of eastern bracken.

ABSTRACT:

Background

Liquid suspension culture efficiently proliferates plant cells and can be applied to ferns because it rapidly increases the fresh weight of gametophytes. This study assessed gametophyte proliferation and sporophyte production of Pteridium aquilinum var. latiusculum using a suspension culture method.

Results

The growth curve linear phase of gametophyte cells was confirmed between 9 and 18 days of culture, and the subculture cycle was determined to be 2 weeks. A double-strength MS medium (fresh weight, 18.0 g) containing 2% sucrose and NH₄⁺:NO₃^- (120 mM, 40:80) was found to be the optimal liquid medium. Gametophytes obtained after suspension culture for 18 days did not normally form sporophytes in an ex vitro soil environment. However, this issue was resolved after changing the culture type or extending the culture period to 6 weeks. A short suspension culture period increased the fresh weight of fragmented and homogenized gametophytes but yielded numerous relatively immature gametophytes (globular forms of branching gametophytes, BG). Furthermore, differences in gametophyte morphogenesis and development were indicated by changes in endogenous phytohormone content. BG with immature development exhibited high accumulation of zeatin, jasmonic acid, and salicylic acid, and relatively low levels of abscisic acid and indole-3-acetic acid. The immature development of gametophytes directly affected sporophyte formation.

Conclusions

This study maximized the advantages of liquid suspension culture using eastern bracken gametophytes and provides data to resolve any associated issues, thus facilitating efficient bracken production.

SUBMITTER: Jang BK

PROVIDER: S-EPMC8336368 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND: Because of their phylogenetic position and unique characteristics of their biology and life cycle, ferns represent an important lineage for studying the evolution of land plants. Large and complex genomes in ferns combined with the absence of economically important species have been a barrier to the development of genomic resources. However, high throughput sequencing technologies are now being widely applied to non-model species. We leveraged the Roche 454 GS-FLX Titanium pyrosequencing platform in sequencing the gametophyte transcriptome of bracken fern (Pteridium aquilinum) to develop genomic resources for evolutionary studies. RESULTS: 681,722 quality and adapter trimmed reads totaling 254 Mbp were assembled de novo into 56,256 unique sequences (i.e. unigenes) with a mean length of 547.2 bp and a total assembly size of 30.8 Mbp with an average read-depth coverage of 7.0×. We estimate that 87% of the complete transcriptome has been sequenced and that all transcripts have been tagged. 61.8% of the unigenes had blastx hits in the NCBI nr protein database, representing 22,596 unique best hits. The longest open reading frame in 52.2% of the unigenes had positive domain matches in InterProScan searches. We assigned 46.2% of the unigenes with a GO functional annotation and 16.0% with an enzyme code annotation. Enzyme codes were used to retrieve and color KEGG pathway maps. A comparative genomics approach revealed a substantial proportion of genes expressed in bracken gametophytes to be shared across the genomes of Arabidopsis, Selaginella and Physcomitrella, and identified a substantial number of potentially novel fern genes. By comparing the list of Arabidopsis genes identified by blast with a list of gametophyte-specific Arabidopsis genes taken from the literature, we identified a set of potentially conserved gametophyte specific genes. We screened unigenes for repetitive sequences to identify 548 potentially-amplifiable simple sequence repeat loci and 689 expressed transposable elements. CONCLUSIONS: This study is the first comprehensive transcriptome analysis for a fern and represents an important scientific resource for comparative evolutionary and functional genomics studies in land plants. We demonstrate the utility of high-throughput sequencing of a normalized cDNA library for de novo transcriptome characterization and gene discovery in a non-model plant.